1. Field of the Invention
The invention is in the field of textile technology and relates to an apparatus which is used for the continuous crimping of threads made from thermoplastic material.
2. Discussion of the Background of the Invention and Material Information
During the continuous crimping of threads (fibril bundles) made from thermoplastic material, they are e.g. moved through a feed channel with the aid of a pressurized, flowing, hot feed medium, heated and then fed through a nozzle orifice into a stuffer box, the latter being designed in such a way that the feed medium is expanded on passing out of the nozzle orifice. In the stuffer box the thread strikes against a plug formed from thread previously passed out of the orifice and thus crimping occurs. The plug is then conveyed in the feed channel at a speed lower than the thread speed and is cooled and, in the further process is loosened or opened to form a textured yarn.
European patent document No. 310890, as well as cognate U.S. Pat. Nos. 4,877,570 and 4,974,302, also assigned to the assignee of the present invention, e.g. describe a process and an apparatus for the continuous crimping of thermoplastic threads. The described apparatus embodiments have a crimping nozzle with a feed channel through which the thread is fed with the aid of a flowing medium against a nozzle orifice and a rotary plug feed roller on which the plug is further conveyed between lateral guide means arranged on the roller circumference, e.g. rows of radially positioned needles. The crimping nozzle is arranged with the nozzle orifice against the plug feed roller and substantially tangentially thereto. Directly outside the nozzle orifice the plug is formed in a stuffer box through stationary guide means, located in the vicinity of the orifice and the lateral guide means, and moved toward the plug feed roller. The plug forming in this stuffer box is defined in such a way that it is positioned between the lateral guide means without coming into contact with the plug feed roller and without extending radially over the guide means. The plug passing out of the stuffer box is so stable that the axial guidance of the lateral guide means is sufficient for its further transfer in the same position.
It has been found that it is important, for the quality of the yarn produced, that the feed medium expands as rapidly as possible, after passing out of the nozzle orifice, i.e. the stuffer box must be well vented. Particularly, in the case of high thread speeds, venting may prove inadequate and there is a negative influence on yarn quality.